1. How was Earth formed?

2. Big Bang Theory 13.7 billion years ago 13.7 billion years ago Creation of all matter Creation of all matter Hydrogen and Helium the first Hydrogen and Helium the first More complex elements evolved through time More complex elements evolved through time

4. The Expanding UniverseUniverse The Doppler effect is used to document the expanding universe

5. Red shift

6. Hubble’s Law Red shift is related to distance The farther galaxies are moving faster than the closer galaxies

7. The Nebula Hypotheses

8. The Nebular Hypothesis The solar system formed from a collapsed nebula 1734 by Emanuel Swedenborg Observations support this idea

9. Nebulae: step 1 Gas (98%) and dust (2%) Rotates and is held together by gravitational force

10. Step 2: The Nebula collapses The collapsed mass forms a proto-sun due to gravitational force Contraction increases speed of rotation: collapse

11. Step 3: sun is formed, disk cleared The disk is “cleared out” due to the immense amount of energy released. Sun is formed Dust and gases cool and condense in defined orbits around the sun

12. Nebula hypothesis: step 4- planet formation Temperature differences with respect to distance from sun Closer, where temperatures are higher, iron and silicates condense Farther, cooler, hydrogen, water condense material collides and accretes forming planetesimals (small planets)

13. Evidence: Orion Nebula Third star down on Orion’s belt 100 light years across (1 light year equals 6 trillion miles) Reflection of dust and hydrogen

14. Evidence: Collapsed nebulae discs found in the Orion nebula Gaseous disks are circling proto-suns. 2-17 times larger than our solar system About 153 protoplanetary disks found in the Orion Nebula

15. EarlyEarly Earth Homogenous Very hot 13:40

16. Compositionally distinct layers Physically distinct layers Segregation of elements: gravitational force Remember: the liquid outer core with the Earth’s rotation produces the magnetic field.